Dobson's father told Britain's Press Association news agency that they had been looking forward to the trip for a long time.

The three were killed when their helicopter crashed Saturday onto the jagged rocks of the Grand Canyon on the Hualapai (WAHL'-uh-peye) reservation outside the boundaries of the national park.

Three other British tourists and the pilot survived and were airlifted to a Las Vegas hospital.

The National Transportation Safety Board and the Federal Aviation Administration are investigating.

___

12:05 a.m.

Authorities say three British tourists died when a sightseeing helicopter they were on crashed onto the jagged rocks of the Grand Canyon. Three other British tourists and the pilot survived and were airlifted to a Las Vegas hospital.

A witness said he saw flames and black smoke spewing from the crash site, heard explosions and saw victims bleeding and badly burned.

The Papillon Grand Canyon Helicopters chopper crashed under unknown circumstances Saturday evening on the Hualapai Nation's land by the Grand Canyon's West Rim

Hualapai Nation Police Chief Francis Bradley says navigating the rugged terrain in the dark made it difficult for first-responders to reach the helicopter's wreckage.

The National Transportation Safety Board and the Federal Aviation Administration are investigating.

The Nevada-based company says it cooperating fully with investigators.